Garrison member Ingrid Moon works on a Clone Trooper helmet at an armor party. Moon is also executive officer of the First Imperial Stormtrooper Detachment.

Courtesy of Ingrid Moon

A short time ago, in a garage not so far away, Steve Leahy was having a problem with his armor. A tiny piece of plastic, maybe just a few millimeters wide, stuck out from the shin guard.

"I know it's a minor detail, and while you're wearing it, someone may never notice," Leahy says. "But I know it's there and I know it shouldn't be, so we like to put the effort in to make it as perfect as possible."

Leahy, a member of the Southern California Garrison of the 501st Legion (Vader's Fist), has a good reason to strive for perfection. For most of the year, they wear their homemade plastic Star Wars armor for parades and charity events.

But Leahy and his fellow Stormtroopers are gearing up for their assault on the ice planet Hoth — Comic Con International: San Diego, which starts Thursday.

So Leahy uses an electric sander to smooth out the errant plastic and then goes over it again with sandpaper until his shin guard is smooth.

Like Civil War re-enactors from this galaxy, the 501st Legion's costuming requirements are strict. To be accepted into the Stormtrooper ranks, a new recruit's armor must have every stripe perfectly painted, every button and divot perfectly placed.

Costumes must pass muster with Drew Hannah, the garrison's inspector.

"Did they paint the trapezoids on the helmet correctly?" Hannah asks. "Are the tube stripes the correct colors? Is the frown the correct color and cut out with the appropriate number of teeth?"

The garrison meets in Hannah's garage in Ventura, Calif., to construct its armor. Stormtroopers can spend up to $8,000 on their costumes and work on them constantly.

Troopers are rushing to finish their costumes in time for Comic Con, but, Hannah says, the garrison's greatest joy is visiting children's hospitals.

"If you were to be able to peak under our helmets, we pretty much have goofy grins or full-blown smiles plastered on our faces," he says.

Why do good deeds while dressed as bad guys? Hannah says the Dark Side costumes are just cooler.

"If you look at it from our point of view, we're the rightful law and order of the galaxy." he explains. "Doesn't matter that our boss is a little on the evil side; to us we're enforcing law and order."

Members of the 501st Imperial Stormtrooper Legion have an unusual hobby. They make their own white plastic armor, you know, the kind from "Star Wars?" For most of the year, they don it for parades and charity events, but as Claire Trageser from member station KPBS reports, now these stormtroopers are gearing up for their assault on the ice planet Hoth.

It's all going down at San Diego's Comic-Con.

CLAIRE TRAGESER, BYLINE: A short time ago, in a garage not so far away, Steve Leahy was having a problem with his armor. There was a tiny piece of plastic, maybe just a few millimeters wide, stuck out from the shin guard.

STEVE LEAHY: I know it's a minor detail and while you're wearing it someone might never notice but I know it's there and I know it shouldn't be, so we like to put the effort in to make it as perfect as possible.

(SOUNDBITE OF ELECTRIC SANDER)

TRAGESER: So Leahy uses an electric sander to smooth it out and then goes over it again with sandpaper.

(SOUNDBITE OF SANDING)

LEAHY: Done deal.

TRAGESER: Leahy has good reason for his obsessions. Like Civil War reenactors from this galaxy, the 501st Legion's costuming requirements are strict. To be accepted into the stormtrooper ranks, a new recruit's armor must have every stripe perfectly painted, every button and divot perfectly places.

DREW HANNAH: Did they paint the trapezoids on the helmet correctly? Are the tube stripes the correct colors?

TRAGESER: Drew Hannah decides which costumes pass muster.

HANNAH: Is the frown the correct color and cut out with the appropriate number of teeth?

TRAGESER: It's Hannah's garage in Ventura where the garrison meets to construct its armor.

HANNAH: Does that look about right, Steve?

LEAHY: Oh, sure. Move it one millimeter to the right.

TRAGESER: Stormtroopers can spend up to $8,000 on their costumes and work on them constantly. Now troopers are rushing to finish their costumes in time for Comic-Con. Still, Hannah says the garrison's greatest joy is visiting children's hospitals.

HANNAH: If you were to be able to peek under our helmets, we pretty much have goofy grins or full-blown smiles plastered on our faces.

TRAGESER: So why do good deeds while dressed as bad guys? Hannah says the dark side costumes are just cooler.

HANNAH: If you look at it from our point of view, we're the rightful law and order of the galaxy. Doesn't matter that our boss is a little on the evil side. To us, we're enforcing law and order.

TRAGESER: Possibly the only dark side, downside is this.

(SOUNDBITE OF MOVIE, "STAR WARS")

CARRIE FISHER: (as Princess Leia) Aren't you short for a stormtrooper?

HANNAH: We hear that particular joke all the time, even if we are the correct height for a stormtrooper.

TRAGESER: And Hannah is the exact right height, 5'11". For NPR News, I'm Claire Trageser in San Diego.